[weblacky]

I've taken a quick look under the PIMM and there appear to be these small array SMDs (maybe higher wattage resistor arrays) around the chips between the Cache chips and the CPU. It's at least a starting point if I can find the pins referred to on the cache chips, then back tracing them. It's possible there is a cracked solder joint or a bad (out of spec) protection resistor in the array or something hindering communication.

My gut still says something is interfering, versus something inside the cache or the CPU is broken. The pattern of disruption is just so small, I'd believe it falls on a single line or maybe two. I didn't immediately see anything that looking like a multiplexer or anything positioned between them for communication.

I'll update when I have more.